Regulation of coagulation by protein S:

The natural anticoagulant protein S; hemostatic functions and deficiency

Protein S (PS) is a vital endogenous anticoagulant. It plays a crucial role in regulating coagulation by acting as a cofactor for the activated protein C (APC) and tissue factor pathway inhibitor (TFPI) pathways. Additionally, it possesses direct anticoagulant properties by impeding the intrinsic tenase and prothrombinase complexes. Protein S oversees the coagulation process in both the initiation and propagation stages through these roles. The significance of protein S in regulating blood clotting can be inferred from the significant correlation between deficits in protein S and an elevated susceptibility to venous thrombosis. This is likely because activated protein C and tissue factor pathway inhibitor exhibit low efficacy as anticoagulants when no cofactors exist. The precise biochemical mechanisms underlying the roles of protein S cofactors have yet to be fully elucidated. Nevertheless, recent scientific breakthroughs have significantly enhanced comprehension findings for these functions. The diagnosis of protein S deficiency, both from a technical and genetic standpoint, is still a subject of debate due to the complex structural characteristics of the condition. This paper will provide an in-depth review of the molecular structure of protein S and its hemostatic effects. Furthermore, we shall address the insufficiency of protein S and its methods of diagnosis and treatment.

Replication Study of the Association of GAS6 and PROS1 Polymorphisms with Behçet's Disease in a Japanese Population

PURPOSE

To investigate whether polymorphisms of GAS6 and PROS1, which each encode protein ligands for a family of tyrosine kinase receptors, are associated with Behçet's disease (BD) in a Japanese population.

METHODS

We recruited 734 Japanese patients with BD and 1789 Japanese healthy controls. In all participants, we genotyped two single-nucleotide polymorphisms (SNPs) reportedly associated with BD: rs9577873 in GAS6 and rs4857037 in PROS1.

RESULTS

We found that GAS6 rs9577873 was not significantly associated with BD. In contrast, PROS1 rs4857037, specifically the A allele, was associated with increased risk for BD. The A allele was also significantly associated with BD under additive and recessive genetic models. Expression analysis revealed that this allele was significantly associated with increased PROS1 expression.

CONCLUSIONS

Our findings suggest that increased PROS1 expression related to the A risk allele of rs4857037 affects tyrosine kinase receptor signaling, contributing to the development of BD.

In Situ Endothelial SARS-CoV-2 Presence and PROS1 Plasma Levels Alteration in SARS-CoV-2-Associated Coagulopathies

BACKGROUND

Coagulation decompensation is one of the complications most frequently encountered in COVID-19 patients with a poor prognosis or long-COVID syndrome, possibly due to the persistence of SARS-CoV-2 infection in the cardiovascular system. To date, the mechanism underlying the alteration of the coagulation cascade in COVID-19 patients remains misunderstood and the anticoagulant protein S (PROS1) has been described as a potential risk factor for complications related to COVID-19, due to PLpro SARS-CoV-2 enzyme proteolysis.

METHODS

Biopsies and blood samples were collected from SARS-CoV-2 positive and negative swab test subjects with coagulopathies (peripheral arterial thrombosis), and SARS-CoV-2 presence, ACE2 and CD147 expression, and plasmatic levels of PROS1 were evaluated.

RESULTS

We reported a significant decrease of plasmatic PROS1 in the coagulopathic SARS-CoV-2 swab positive cohort, in association with SARS-CoV-2 in situ infection and CD147 peculiar expression. These data suggested that SARS-CoV-2 associated thrombotic/ischemic events might involve PROS1 cleavage by viral PLpro directly in the site of infection, leading to the loss of its anticoagulant function.

CONCLUSIONS

Based on this evidence, the identification of predisposing factors, such as CD147 increased expression, and the use of PLpro inhibitors to preserve PROS1 function, might be useful for COVID-19 coagulopathies management.

The calcium-clot connection: investigating the association between primary hyperparathyroidism and acute venous thromboembolism

Primary hyperthyroidism (PHPT) is a relatively uncommon disease and leads to increased calcium levels. Ionized calcium, known as clotting Factor IV, may lead to overt coagulation cascade activation, increasing the risk of venous thromboembolism (VTE). National Inpatient Sample Database was used to sample individuals with primary hyperparathyroidism, and baseline demographics and comorbidities were collected using ICD-10 codes. Patients with missing data and age less than 18 were excluded. Moreover, patients with other types of hyperparathyroidism and risk factors for VTE, such as malignancy, thrombophilia, chronic kidney and liver disease, fractures, trauma, oral contraceptive/steroid use, and organ transplant, were excluded. Greedy propensity matching using R was performed to match patients with and without primary hyperparathyroidism on age, race, gender, and 10 other comorbidities, including chronic deep venous thromboembolism. Univariate analysis pre- and post-match were performed. Binary logistic regression was performed after matching to assess whether primary hyperparathyroidism was an independent risk factor for acute VTE. A p-value of  < 0.05 was considered statistically significant. Out of 460,529 patients included in the study, 1114 (6.5%) had PHPT. Baseline comorbidities were more common in the PHPT group. On univariate analysis, patients with PHPT were more likely to have acute VTE (2.5% vs. 1.4%; p < 0.001). After 1:1 matching, PHPT patients were twice as likely to have Acute VTE. (OR: 2.1 [1.08-4.1]; p < 0.025). These findings suggest an association between PHPT and VTE, which should be further investigated to prevent the increasing incidence of VTE and its recurrence.

Unprovoked Venous Thromboembolism: The Search for the Cause

Venous thromboembolism (VTE) is a common vascular disorder encompassing deep vein thrombosis (DVT) and pulmonary embolism (PE). There is no data on global estimates of VTE prevalence and incidence. Most patients with unprovoked VTE require secondary thromboprophylaxis upon the completion of the primary treatment phase if they have no high bleeding risk. Risk prediction models can help identify patients at low VTE recurrence risk who may discontinue anticoagulation upon the completion of the primary treatment phase.

The impact of PROS1 mutation position on thrombotic risk in protein S-deficient patients

Background

Inherited protein S deficiency is a thrombophilic risk factor associated with venous thromboembolism. However, there is not much data on the impact of mutation position on thrombotic risk.

Objectives

The aim of this study was to evaluate the risk of thrombosis due to mutations located in the sex hormone-binding globulin (SHBG)-like region as opposed to the rest of the protein.

Methods

Genetic analysis of PROS1 was performed in 76 patients with suspected inherited protein S deficiency, and the effect of missense mutations present in the SHBG region on thrombosis risk was analyzed by statistical methods.

Results

We found 30 unique mutations (13 of them novel), of which 17 were missense mutations, in 70 patients. Patients with missense mutations were then divided into 2 groups: the "SHBG-region" mutation group (27 patients) and the "non-SHBG" group (24 patients). The multivariable binary logistic regression analysis showed that mutation position in the SHBG region of protein S is an independent risk factor for thrombosis in deficient patients (OR, 5.17; 95% CI, 1.29-20.65; P = .02). The patients with a mutation in the SHBG-like region also developed a thrombotic event at a younger age compared to the "non-SHBG" group in the Kaplan-Meier analysis (median thrombosis-free survival of 33 vs 47 years, respectively; P = .018).

Conclusion

Our findings show that a missense mutation located in the SHBG-like region may contribute to higher thrombotic risk rather than a missense mutation located elsewhere in the protein. However, as our cohort was relatively small, these findings should be taken with this limitation.

Phosphatidylserine-Exposing Annexin A1-Positive Extracellular Vesicles: Potential Cancer Biomarkers

Under physiological conditions, phosphatidylserine (PS) predominantly localizes to the cytosolic leaflet of the plasma membrane of cells. During apoptosis, PS is exposed on the cell surface and serves as an “eat-me” signal for macrophages to prevent releasing self-immunogenic cellular components from dying cells which could potentially lead to autoimmunity. However, increasing evidence indicates that viable cells can also expose PS on their surface. Interestingly, tumor cell-derived extracellular vesicles (EVs) externalize PS. Recent studies have proposed PS-exposing EVs as a potential biomarker for the early detection of cancer and other diseases. However, there are confounding results regarding subtypes of PS-positive EVs, and knowledge of PS exposure on the EV surface requires further elucidation. In this study, we enriched small EVs (sEVs) and medium/large EVs (m/lEVs) from conditioned media of breast cancer cells (MDA-MB-231, MDA-MB-468) and non-cancerous cells (keratinocytes, fibroblasts). Since several PS-binding molecules are available to date, we compared recombinant proteins of annexin A5 and the carboxylated glutamic acid domain of Protein S (GlaS), also specific for PS, to detect PS-exposing EVs. Firstly, PS externalization in each EV fraction was analyzed using a bead-based EV assay, which combines EV capture using microbeads and analysis of PS-exposing EVs by flow cytometry. The bulk EV assay showed higher PS externalization in m/lEVs derived from MDA-MB-468 cells but not from MDA-MB-231 cells, while higher binding of GlaS was also observed in m/lEVs from fibroblasts. Second, using single EV flow cytometry, PS externalization was also analyzed on individual sEVs and m/lEVs. Significantly higher PS externalization was detected in m/lEVs (annexin A1+) derived from cancer cells compared to m/lEVs (annexin A1+) from non-cancerous cells. These results emphasize the significance of PS-exposing m/lEVs (annexin A1+) as an undervalued EV subtype for early cancer detection and provide a better understanding of PS externalization in disease-associated EV subtypes.

Blood transcriptome responses to PFOA and GenX treatment in the marsupial biomedical model Monodelphis domestica

Introduction: Perfluoroalkyl and poly-fluoroalkyl substances (PFASs) are widely used in industrial and consumer products. Due to their environmental persistence and bioaccumulation, PFASs can be found in the blood of humans and wild animals all over the world. Various fluorinated alternatives such as GenX have been developed to replace the long-chain PFASs, but there is limited information about their potential toxicity. Methods:The current study developed blood culture protocols to assess the response to toxic compounds in the marsupial, Monodelphis domestica. After whole-blood culture conditions were tested and optimized, changes in gene expression in response to PFOA and GenX treatment were assessed. Results: More than 10,000 genes were expressed in the blood transcriptomes with and without treatment. Both PFOA and GenX treatment led to significant changes in the whole blood culture transcriptomes. A total of 578 and 148 differentially expressed genes (DEGs) were detected in the PFOA and GenX treatment groups, 32 of which overlapped. Pathway enrichment analysis revealed that DEGs involved in developmental processes were upregulated after PFOA exposure, while those enriched for metabolic and immune system processes were downregulated. GenX exposure upregulated genes associated with fatty acid transport pathways and inflammatory processes, which is consistent with previous studies using rodent models. Discussion: To our knowledge, this study is the first to investigate the effect of PFASs in a marsupial model. The findings provide supportive evidence for significant transcriptomic alterations, suggesting that this mammalian model may provide a mechanism for exploring the potential toxicity of PFOA and GenX.

Endothelial Cells and the Cerebral Circulation

Endothelial cells form the innermost layer of all blood vessels and are the only vascular component that remains throughout all vascular segments. The cerebral vasculature has several unique properties not found in the peripheral circulation; this requires that the cerebral endothelium be considered as a unique entity. Cerebral endothelial cells perform several functions vital for brain health. The cerebral vasculature is responsible for protecting the brain from external threats carried in the blood. The endothelial cells are central to this requirement as they form the basis of the blood-brain barrier. The endothelium also regulates fibrinolysis, thrombosis, platelet activation, vascular permeability, metabolism, catabolism, inflammation, and white cell trafficking. Endothelial cells regulate the changes in vascular structure caused by angiogenesis and artery remodeling. Further, the endothelium contributes to vascular tone, allowing proper perfusion of the brain which has high energy demands and no energy stores. In this article, we discuss the basic anatomy and physiology of the cerebral endothelium. Where appropriate, we discuss the detrimental effects of high blood pressure on the cerebral endothelium and the contribution of cerebrovascular disease endothelial dysfunction and dementia. © 2022 American Physiological Society. Compr Physiol 12:3449-3508, 2022.

Protein S Erlangen: a novel PROS1 gene mutation associated with quantitative protein S deficiency

The members of a Caucasian family were genetically analyzed on suspicion of hereditary protein S deficiency. A novel mutation, c.1904T>C, associated with severe quantitative protein S deficiency was found. The novel PROS1 mutation was identified by sequencing of the PROS1 gene coding sequence. The identified c.1904T>C point mutation results in p.Phe635Ser amino acid exchange, which is located in the Laminin G-like 2 domain of protein S. Computational analysis indicates that this amino acid exchange affects the correct folding of the protein S antigen. Furthermore, this mutation is located in a region of the Laminin G-like 2 domain where changes in the amino acid sequence often result in decreased secretion. We postulate that the novel p.Phe635Ser mutation might lead to an incorrect folding, and thus, to a strongly impaired secretion of this protein S variant. We named this novel variant protein.

Cerebral venous sinus thrombosis and dural arteriovenous fistula associated with protein S deficiency: a case series study

OBJECTIVE

To describe the characteristics of patients with cerebral venous sinus thrombosis (CVST) and dural arteriovenous fistula (AVF) associated with protein S (PS) deficiency.

METHODS

We conducted a search of medical records in Hainan General Hospital from January 2000 to December 2020 for coexistence of CVST and dural AVF associated with PS deficiency and searched PubMed、Embase and Chinese biomedical databases (CBM) for all literature describing CVST and dural AVF with PS. We analyzed clinical characteristics, location, sequence of CVST and dural AVF, level of PS, therapeutic methods and prognosis.

RESULTS

We presented 1 patient in our hospital's database combined CVST and dural AVF associated with PS, plus 5 cases reported in literature. The most common symptoms were headache, generalized seizure, disturbance of consciousness. The most frequent location of CVST was at internal cerebral vein, while transverse sinus, sigmoid sinus, parietal region in dural AVF. Two patients developed dural AVF several months or years after CVST. Clinical characteristics and level of PS were summarized.

CONCLUSION

These findings alert physicians to consider PS deficiency in patients who suffer from CVST, especially those combined with dural AVF.

Venous Thromboembolism in Kidney Diseases and Genetic Predisposition

BACKGROUND

Many renal diseases have been associated with profound clinical effects on thrombosis. To our knowledge, patients with nephrotic syndrome (NS) and chronic kidney disease (CKD) display an elevated risk of vein thrombosis, which is among the common causes of mortality in patients with renal diseases. In addition, venous thrombosis, as a complication, has also been reported in a variety of other renal diseases such as glomerulonephritis without the NS, hypertensive nephropathy, and polycystic kidney disease. With the increasing incidence of kidney diseases and the deeper understanding of the disease, clinicians are becoming more and more aware of the complications of thrombus formation in kidney disease.

SUMMARY

We reviewed recent publications of vein thrombosis in kidney diseases, including primary and secondary glomerular diseases, CKD, hereditary kidney disease, renal transplantation, and hemodialysis-induced, catheter-related thrombus, focusing mainly on the main clinical manifestations, possible mechanisms, related risk factors as well as hereditary influencing factors.

KEY MESSAGES

Vein thrombosis is a complicated complication of a wide spectrum of kidney diseases due to different possible underlying mechanisms.

How can Secondary Thromboprophylaxis in High-Risk Pregnant Patients be Improved?

Low-molecular-weight heparin (LMWH) is suggested for thromboprophylaxis in pregnant women with previous venous thromboembolism (VTE). Anyway, there is only limited amount of studies evaluating the effect of LMWH on hemostatic parameters during pregnancy of patients with previous VTE and the need of secondary thromboprophylaxis. We therefore provide results of prospective and longitudinal assessment of changes in hemostasis in high-risk pregnant women at four times during pregnancy (T1–T4) and one time after the postpartum period (T5) used for individualized modification of thromboprophylaxis. In this study, the results of coagulation factor VIII (FVIII) and protein S (PS) activity, ProC Global ratio and anti-Xa activity were evaluated. Despite the thromboprophylaxis, an increased predisposition to thromboembolic complications was detected (significant increase in FVIII activity and decrease in PS function, ProC Global ratio not normalized even after the postpartum period – p < .0001 between controls and T5 for PS and ProC Global). These results indicate that hemostasis may not be restored even 6 to 8 weeks after delivery and pose the question when is it safe to withdraw the anticoagulant thromboprophylaxis in high-risk patients with prior VTE.

Cost-Effective Use of the Protein S Algorithm in Thrombophilia Testing

Background

One of the most complex risk factors for the laboratory assessment of thrombophilia is Protein S (PS). The testing algorithm for PS employs the plasma-based assays of free PS antigen, total PS antigen, and PS activity creating a complex diagnostic scheme that can lead to misdiagnosis if incorrectly used, and a potential waste of resources and money.

Content

This paper compares the recently published evidence-based algorithm from the International Society for Hemostasis and Thrombosis (ISTH) with several commonly performed nonevidence-based testing schemes, to demonstrate the efficiency of the evidence-based algorithm for diagnostic efficiency with improved patient care and increased cost savings for the laboratory.

Summary

Significant savings (31%–60%) can be realized when the evidence-based algorithm is used in place of other testing modalities of initial PS activity testing (31%) or testing with all 3 assays simultaneously (60%). This study utilizing the PS testing evidence-based algorithm as part of a thrombophilia evaluation demonstrates that the appropriate testing methods can be used to limit wasteful practices while achieving the maximum level of information in this time of limited resources and need for increase monetary savings.

The role of phosphatidylserine on the membrane in immunity and blood coagulation

The negatively charged aminophospholipid, phosphatidylserine (PtdSer), is located in the inner leaflet of the plasma membrane in normal cells, and may be exposed to the outer leaflet under some immune and blood coagulation processes. Meanwhile, Ptdser exposed to apoptotic cells can be recognized and eliminated by various immune cells, whereas on the surface of activated platelets Ptdser interacts with coagulation factors prompting enhanced production of thrombin which significantly facilitates blood coagulation. In the case where PtdSer fails in exposure or mistakenly occurs, there are occurrences of certain immunological and haematological diseases, such as the Scott syndrome and Systemic lupus erythematosus. Besides, viruses (e.g., Human Immunodeficiency Virus (HIV), Ebola virus (EBOV)) can invade host cells through binding the exposed PtdSer. Most recently, the Corona Virus Disease 2019 (COVID-19) has been similarly linked to PtdSer or its receptors. Therefore, it is essential to comprehensively understand PtdSer and its functional characteristics. Therefore, this review summarizes Ptdser, its eversion mechanism; interaction mechanism, particularly with its immune receptors and coagulation factors; recognition sites; and its function in immune and blood processes. This review illustrates the potential aspects for the underlying pathogenic mechanism of PtdSer-related diseases, and the discovery of new therapeutic strategies as well.

Rapid identification of a pathogenic variant of PROS1 in a thrombophilic family by whole exome sequencing: A case report

RATIONALE

Venous thrombosis remains a significant problem in modern days. Genetic factors contribute to a subset of patients with venous thrombosis. It is sometimes challenging to identify the underlying culprit in thrombophilic individuals based on traditional laboratory testing and Sanger sequencing.

PATIENT CONCERNS

A thrombophilic family presented with multiple venous thrombosis was examined.

DIAGNOSES

Molecular genetic analysis revealed a pathogenic missense variant of the PROS1 gene. Based on this finding and clinical manifestations, a final diagnosis of protein S deficiency was made.

INTERVENTIONS

Whole exome sequencing (WES) of the proband was performed to identify disease-causing variants. Subsequently, Sanger sequencing was performed to validate the variant in the affected members.

OUTCOMES

Using WES, we rapidly identified a proven pathogenic missense variant (c.1543C > T, p.Arg515Cys) in the sex hormone-binding globulin domain of PROS1, which was confirmed by Sanger sequencing. The decreased level and activity of protein S caused by the variant explained the phenotypes of the family. Patients received rivaroxaban as a long-term anticoagulation therapy and achieved a good prognosis.

LESSONS

Our study suggests WES as a rapid search strategy to identify the genetic factors underlying thrombophilic disorders. Patients with venous thrombosis caused by PROS1 mutations could receive rivaroxaban as the first choice of anticoagulation therapy.

A Rare Thrombophilic Occurrence: Dural Venous Sinus Thrombosis in a Patient with Significant Family History of Protein S Deficiency

Protein S is a potent anticoagulant that downregulates thrombin formation and is a vitamin K-dependent glycoprotein which is primarily synthesized in the liver. A deficiency in this protein or decreased activity, as seen in hereditary protein S deficiency, can lead to life-threatening thrombosis. Hereditary protein S deficiency is a rare disease as listed by the National Organization for Rare Disorders (NORD). It is known to cause venous as well as arterial thromboembolic events commonly occurring in the deep leg and pelvic veins. Dural venous sinus thrombosis is a rare consequence of protein S deficiency and is associated with a risk of increased morbidity and mortality. We report a case of dural venous sinus thrombosis in a patient with a family history of protein S deficiency in nine family members. A 53-year-old female presented to the ED with a three-day history of persistent left-sided headache, left facial numbness with tingling, and photophobia. She denied any visual disturbances, slurring of speech, and/or unilateral weakness. Some 10 years prior to this episode, she was placed on warfarin therapy for deep vein thrombosis (DVT) of lower extremity, but she discontinued it after three years of treatment without consulting her treating physician. She was taking oral contraceptive pills (OCPs) for two years and discontinued one month ago. She has nine family members with protein S deficiency, but the patient was never screened for a hypercoagulable state. On admission, her vital signs were within normal limits. Pupils were round and reactive to light, neck was supple, there was a sensory deficit for pinprick on the left V2-V3 distribution, and remainder of the cranial nerves and neurologic examination was unremarkable. CT scan of the head demonstrated a hyper-density within the left transverse and sigmoid sinus suspicious for dural venous sinus thrombosis. This was confirmed by CT angiogram showing a filling defect throughout the transverse sinus and sigmoid sinus extending below the jugular bulb into the superior aspect of the jugular vein. Intravenous heparin and warfarin were initiated. As the patient had severe trypanophobia and IV heparin required frequent activated partial thromboplastin time (APTT) monitoring, this was later changed to subcutaneous low-molecular-weight heparin and warfarin. Subsequent thrombosis panel showed a reduced protein S activity of 15% and low levels of total and free protein S antigens. She was discharged home with life-long warfarin therapy. In conclusion, cerebral dural venous sinus thrombosis is a rare and potentially life-threatening condition that can be seen in hereditary protein S deficiency. A high degree of suspicion in young females with worsening headache and neurologic signs and symptoms will help with timely diagnosis and management avoiding serious consequences. In a patient with a family history of thrombophilia, as seen in our patient, screening is important in order to confirm an underlying thrombophilic state. Such testing may have helped our patient regarding education on avoiding potential risk factors for thrombophilia and importance of treatment adherence.

Contribution of gut microbiota and multiple organ failure in the pathogenesis of COVID-19 infection

COVID-19, which originated in Wuhan, China, has spread rapidly all over the world. An increasing number of COVID-19 cases are caused by human-to-human transmission via respiratory droplets, coughs, and sneezes. The symptoms of COVID-19 patients are heterogeneous, ranging from mild upper respiratory symptoms (fever, languidness, unstable walking, dry cough, fatigue, and respiratory symptoms) to severe pneumonitis and even acute respiratory distress syndrome (ARDS) or death. COVID-19 invades human respiratory epithelial cells by binding with angiotensin-converting enzyme 2 (ACE2) receptors on human cell surfaces. Death in COVID-19 patients is caused by multiorgan function failure. In addition, systemic immune overactivation due to COVID-19 infection produces elevated expression of proinflammatory cytokines and chemokines, resulting in a so-called cytokine storm, a process that is an important factor in COVID-19 disease progression and multiple organ failure leading to death.

Early Protein Markers of Necrotizing Enterocolitis in Plasma of Preterm Pigs Exposed to Antibiotics

Background: Most hospitalized preterm infants receive antibiotics in the first days of life to prevent or treat infections. Short-term, early antibiotic treatment may also prevent the microbiota-dependent gut inflammatory disorder, necrotizing enterocolitis (NEC). It remains a challenge to predict NEC, and a few early blood diagnostic markers exist. Using preterm pigs as model for infants, blood parameters and plasma proteins affected by early progression of NEC were profiled in preterm pigs subjected to oral, systemic, or no antibiotics after preterm birth.

Methods: Preterm newborn pigs were treated with saline (CON) or antibiotics (ampicillin, gentamicin, and metronidazole) given enterally (ENT) or parenterally (PAR), and fed formula for 4 days to induce variable microbiome-dependent sensitivities to NEC. The gut was collected for macroscopic scoring of NEC lesions and blood for hematology, blood biochemistry, and LC/MS-based plasma proteomics. Statistical modeling was applied to detect plasma proteins affected by NEC and/or antibiotics.

Results: Analyzed across different antibiotic regimens, NEC progression was associated with altered blood parameters and abundance of 89 plasma proteins that were functionally involved in extracellular membrane destruction, lipid metabolism, coagulopathy, and acute phase response. Large NEC-related changes were observed in abundance of RBP4, FGA, AHSG, C5, PTPRG, and A-1-antichymotrypsin 2, indicating potential serving as early markers of NEC. Conversely, antibiotic treatment, independent of NEC, affected only 4 proteins with main differences found between ENT and CON pigs.

Conclusion: Early postnatal development of NEC lesions is associated with marked plasma protein changes that may be used for early NEC diagnosis.

A novel rare c.-39C>T mutation in the PROS1 5'UTR causing PS deficiency by creating a new upstream translation initiation codon

Autosomal dominant inherited Protein S deficiency (PSD) (MIM 612336) is a rare disorder caused by rare mutations, mainly located in the coding sequence of the structural PROS1 gene, and associated with an increased risk of venous thromboembolism. To identify the molecular defect underlying PSD observed in an extended French pedigree with seven PSD affected members in whom no candidate deleterious PROS1 mutation was detected by Sanger sequencing of PROS1 exons and their flanking intronic regions or via an multiplex ligation-dependent probe amplification (MLPA) approach, a whole genome sequencing strategy was adopted. This led to the identification of a never reported C to T substitution at c.-39 from the natural ATG codon of the PROS1 gene that completely segregates with PSD in the whole family. This substitution ACG→ATG creates a new start codon upstream of the main ATG. We experimentally demonstrated in HeLa cells that the variant generates a novel overlapping upstream open reading frame (uORF) and inhibits the translation of the wild-type PS. This work describes the first example of 5'UTR PROS1 mutation causing PSD through the creation of an uORF, a mutation that is not predicted to be deleterious by standard annotation softwares, and emphasizes the need for better exploration of such type of non-coding variations in clinical genomics.

Cleavage of proteoglycans, plasma proteins and the platelet-derived growth factor receptor in the hemorrhagic process induced by snake venom metalloproteinases

Envenoming by viperid snakes results in a complex pattern of tissue damage, including hemorrhage, which in severe cases may lead to permanent sequelae. Snake venom metalloproteinases (SVMPs) are main players in this pathogenesis, acting synergistically upon different mammalian proteomes. Hemorrhagic Factor 3 (HF3), a P-III class SVMP from Bothrops jararaca, induces severe local hemorrhage at pmol doses in a murine model. Our hypothesis is that in a complex scenario of tissue damage, HF3 triggers proteolytic cascades by acting on a partially known substrate repertoire. Here, we focused on the hypothesis that different proteoglycans, plasma proteins, and the platelet derived growth factor receptor (PDGFR) could be involved in the HF3-induced hemorrhagic process. In surface plasmon resonance assays, various proteoglycans were demonstrated to interact with HF3, and their incubation with HF3 showed degradation or limited proteolysis. Likewise, Western blot analysis showed in vivo degradation of biglycan, decorin, glypican, lumican and syndecan in the HF3-induced hemorrhagic process. Moreover, antithrombin III, complement components C3 and C4, factor II and plasminogen were cleaved in vitro by HF3. Notably, HF3 cleaved PDGFR (alpha and beta) and PDGF in vitro, while both receptor forms were detected as cleaved in vivo in the hemorrhagic process induced by HF3. These findings outline the multifactorial character of SVMP-induced tissue damage, including the transient activation of tissue proteinases, and underscore for the first time that endothelial glycocalyx proteoglycans and PDGFR are targets of SVMPs in the disruption of microvasculature integrity and generation of hemorrhage.

Outcomes of left ventricular assist device implantation in hypercoagulable patients

BACKGROUND

The aim of this study was to evaluate outcomes of left ventricular assist devices (LVADs) in patients who tested positive for hypercoagulable hematologic disorders.

METHODS

Adults undergoing continuous-flow LVAD implantation with preoperative hypercoagulability testing between 2004 and 2018 at a single center were reviewed. Hypercoagulability was defined as testing positive for antiphospholipid antibody, anticardiolipin antibody, lupus anticoagulant, protein C, protein S, factor V Leiden, and/or heparin-induced thrombocytopenia. The primary outcome was survival on the original LVAD. Secondary outcomes included rates of thromboembolic complications and readmission for intravenous heparin treatment.

RESULTS

A total of 270 LVAD patients with pre-implant hypercoagulability testing were included, and 157 (58%) tested positive for a hypercoagulable disorder. Of those testing positive, 10 (6.4%) had a clinical pre-LVAD history of thromboembolic events. Survival was comparable between hypercoagulable and non-hypercoagulable patients (1 year: 73.3% vs 78.9%, P = .2195, 2-year: 60.7% vs 62.8%, P = .3627). Rates of pump thrombosis (14.0% vs 13.3%, P = .8618), hemolysis (4.5% vs 3.5%, P = .3536), stroke (18.5% vs 14.2%, P = .3483) and readmission for IV heparin therapy (87.3% (n = 137) vs 77.9% (n = 88), P = .7560) were similar. Outcomes were comparable in patients with positive hypercoagulable tests when stratified by pre-implant clinical history of hypercoagulability as well as stratified by recent preoperative exposure to heparin or warfarin.

CONCLUSIONS

In this series, positive laboratory tests for hypercoagulability were common amongst patients undergoing LVAD implantation although few had positive clinical histories. Survival and freedom from thromboembolic complications were comparable to non-hypercoagulable patients. Hypercoagulability alone should therefore not serve as a contraindication to LVAD implantation.

Open abdomen management for massive intestinal infarction due to acute splanchnic venous thrombosis in a patient with protein S deficiency. A case report

INTRODUCTION

Acute mesenteric ischemia (AMI) refers to the sudden onset of intestinal hypoperfusion that can also result from splanchnic venous occlusion. The portomesenteric venous system (PMVS) is an unusual site of thrombosis in patients with protein S deficiency and its obstruction is a rare cause of AMI. Aim of this report is to illustrate a successful strategy in a case of massive small bowel infarction managed with an open abdomen (OA) approach.

CASE PRESENTATION

A 64 year-old woman presented to the emergency department with acute abdominal pain, rectal bleeding, diarrhea and vomiting. Contrast-enhanced computed tomography (CECT) showed small bowel ischemia and the complete occlusion of all the PMVS branches. Surgery was performed with an OA approach and anticoagulation was immediately begun. Further workup revealed isolated protein S deficiency and history of atrophic gastritis. Thromboprophylaxis with warfarin was started on discharge and no recurrence of thrombotic events was recorded during the one-year follow-up.

DISCUSSION

PMVS thrombosis related to protein S deficiency is a rare condition that can rapidly lead to an acute abdomen. CECT is the gold standard, because it detects splanchnic thrombosis and its possible complications, like bowel ischemia. In case of surgery, a planned second-look operation is the best strategy to assess bowel viability and possible ischemic progression.

CONCLUSIONS

OA management plays a fundamental role in case of resection for bowel ischemia. Patients with thrombosis at an uncommon site should be further investigated for prothrombotic states.

Ischemic stroke and cerebral venous sinus thrombosis in pregnancy

Maternal ischemic stroke and cerebral venous sinus thrombosis (CVST) are dreaded complications of pregnancy and major contributors to maternal disability and mortality. This chapter summarizes the incidence and risk factors for maternal arterial ischemic stroke (AIS) and CVST and discusses the pathophysiology of maternal AIS and CVST. The diagnosis, treatment, and secondary preventive strategies for maternal stroke are also reviewed. Special populations at high risk of maternal stroke, including women with moyamoya disease, sickle cell disease, HIV, thrombophilia, and genetic cerebrovascular disorders, are highlighted.

Deep proteome profiling of the hippocampus in the 5XFAD mouse model reveals biological process alterations and a novel biomarker of Alzheimer's disease

Alzheimer’s disease (AD), which is the most common type of dementia, is characterized by the deposition of extracellular amyloid plaques. To understand the pathophysiology of the AD brain, the assessment of global proteomic dynamics is required. Since the hippocampus is a major region affected in the AD brain, we performed hippocampal analysis and identified proteins that are differentially expressed between wild-type and 5XFAD model mice via LC-MS methods. To reveal the relationship between proteomic changes and the progression of amyloid plaque deposition in the hippocampus, we analyzed the hippocampal proteome at two ages (5 and 10 months). We identified 9,313 total proteins and 1411 differentially expressed proteins (DEPs) in 5- and 10-month-old wild-type and 5XFAD mice. We designated a group of proteins showing the same pattern of changes as amyloid beta (Aβ) as the Aβ-responsive proteome. In addition, we examined potential biomarkers by investigating secretory proteins from the Aβ-responsive proteome. Consequently, we identified vitamin K-dependent protein S (PROS1) as a novel microglia-derived biomarker candidate in the hippocampus of 5XFAD mice. Moreover, we confirmed that the PROS1 level in the serum of 5XFAD mice increases as the disease progresses. An increase in PROS1 is also observed in the sera of AD patients and shows a close correlation with AD neuroimaging markers in humans. Therefore, our quantitative proteome data obtained from 5XFAD model mice successfully predicted AD-related biological alterations and suggested a novel protein biomarker for AD.

A protein newly implicated in Alzheimer’s disease could serve as a diagnostic biomarker or therapeutic target. A team led by Youngsoo Kim and Inhee Mook-Jung from Seoul National University, South Korea, analyzed all the proteins expressed in the hippocampus, the brain’s memory center, in mice with and without Alzheimer’s-like disease. They identified more than 1,400 proteins differentially expressed between the mouse model of Alzheimer’s and the normal mice. Among these were 36 secretory proteins that tended to increase their levels along with build-up of amyloid-beta, the protein found in clumps in the brains of people with Alzheimer’s. Many already had known links to Alzheimer’s, but the researchers also identified a novel protein called PROS1. Blood samples from Alzheimer’s patients also showed an increase in PROS1 levels, with a close correlation with amyloid-beta build-up in the brain.

Study on molecular mechanisms of nattokinase in pharmacological action based on label-free liquid chromatography-tandem mass spectrometry

Cardiovascular diseases (CVDs) are the leading causes of premature death and disability in people around the world. Therefore, the prevention and treatment of CVDs has become an important subject. In this study, we verified the thrombolytic activities of a nattokinase-like protease named NK-01 in vivo. Label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique was used in our study. NK-01 could inhibit the activity of coagulation factors though the up-regulation of proteinase C inhibitors and protein S. NK-01 also could inhibit the angiotensinogen conversion to AngII and promote the degradation of kininogen to reduce the blood pressure. In addition, NK-01 could increase the content of paraoxonase 1, which could prevent atherosclerosis. In our study, we found that NK-01 cloud effect some key proteins which participant in CVDs associated metabolic processes such as coagulation system, blood pressure, and atherosclerosis. Taken together, the underlying molecular mechanisms for the biological beneficial of NK-01 were investigated. Our proteomic study will provide further theoretical basis for application of NK in prevention or adjuvant treatment in biomedicine areas.

Plasma levels of protein C pathway proteins and brain magnetic resonance imaging volumes in multiple sclerosis

BACKGROUND AND PURPOSE

The involvement of protein C (PC) pathway components in multiple sclerosis (MS) has scarcely been explored. The aim was to investigate their levels in relation to clinical and neurodegenerative magnetic resonance imaging (MRI) outcomes in patients.

METHODS

In all, 138 MS patients and 42 healthy individuals were studied. PC, protein S (PS) and soluble endothelial protein C receptor (sEPCR) were evaluated by multiplex assays and enzyme-linked immunosorbent assay. Regression analyses between 3 T MRI outcomes and PC pathway components were performed. ancova was used to compare MRI volumes based on protein level quartiles. Partial correlation was assessed amongst levels of PC pathway components and hemostasis protein levels, including soluble thrombomodulin (sTM), heparin cofactor II (HCII), plasminogen activator inhibitor 1 (PAI-1) and factor XII (FXII). The variation of PC concentration across four time points was evaluated in 32 additional MS patients.

RESULTS

There was an association between PC concentration, mainly reflecting the zymogen PC, and MRI measures for volumes of total gray matter (GM) (P = 0.003), thalamus (P = 0.007), cortex (P = 0.008), deep GM (P = 0.009) and whole brain (P = 0.026). Patients in the highest PC level quartile were characterized by the lowest GM volumes. Correlations of PC-HCII, PC-FXII and sEPCR-sTM values were detectable in MS patients, whilst PC-PS and PS-PAI-1 correlations were present in healthy individuals only.

CONCLUSIONS

Protein C plasma concentrations might be associated with neurodegenerative MRI outcomes in MS. Several differences in correlation amongst protein plasma levels suggest dysregulation of PC pathway components in MS patients. The stability of PC concentration over time supports a PC investigation in relation to GM atrophy in MS.

C1-esterase inhibitor enhances thrombin generation and spatial fibrin clot propagation in the presence of thrombomodulin

Package inserts for C1-esterase inhibitor (C1INH) products include warnings for an elevated risk of possible thrombosis in certain individuals, referring to thromboembolic events (TEEs) that were reported to occur after C1INH infusions. However, the mechanism(s) that could explain possible development of TEEs due to C1INH remains unknown. In this work, we evaluated plausible impact of C1INH on the protein C (PC) anticoagulant system. We performed thrombin generation (TG) assays (TGA) and analyzed spatial fibrin clot propagation using thrombodynamics in plasma of individual donors after the addition of thrombomodulin (TM) and C1INH. The addition of C1INH was consistent with the plasma concentrations resulting from doses currently approved for the HAE treatment up to ones consistent with off-label use in patients with risk of inflammation. 16 IU/ml of C1INH significantly enhanced thrombin peak (TP) generation in the presence of 12 and 15 nM TM. TG enhancement was observed by the addition of C1INH to make concentrations equal to 2 and 4 IU/ml in some donor plasmas. C1INH addition in the presence of TM enhanced the stop time of spatial clot growth in Thrombodynamics assay. A chromogenic activity assay demonstrated that C1INH inhibited PC activation by thrombin in the presence of TM. Substitution of TM with APC in TGA attenuated the TP enhancing effect of C1INH. The collective results of the present study suggest a concentration dependent C1INH interaction with the PC system. This study introduces a plausible TM-dependent mechanism, that may explain reported TEEs via suppressed production of APC in the presence of C1INH.

Identification of PROS1 as a Novel Candidate Gene for Juvenile Retinitis Pigmentosa

Homozygous mutations of PROS1, encoding vitamin K-dependent protein S (PS), have been reported so far to be associated with purpura fulminans, a characteristic fatal venous thromboembolic disorder. The current work for the first time reports the clinical phenotype in patients with juvenile retinitis pigmentosa harboring a novel likely pathogenic variant in thePROS1 gene. Whole-exome sequencing was performed on probands of a cohort with inherited retinal disease. Detailed phenotyping was performed, including clinical evaluation, electroretinography, fundus photography and spectral-domain optical coherence tomography. Analysis of whole-exome and Sanger sequencing led to the identification of a homozygous missense substitution (c.G122C:p.R41P) in PROS1 in affected individuals from two unrelated consanguineous families of Persian origin which had classic retinitis pigmentosa with no history of venous thromboembolic disorder. This variant was segregated, fully congruous with the phenotype in all family members. Consistently, none of 1000 unrelated healthy individuals from the same population carried the mentioned variant, according to Iranian national genome database (Iranome) and additional in-house exome control data. This study provides inaugural clinical traces for different role of PS as a ligand for TAM receptor-mediated efferocytosis at the retinal pigmented epithelium; the R41P variant may affect proper folding of PS needed for γ-carboxylation and extra-cellular secretion. That conformational change may also lead to defective apoptotic cell phagocytosis resulting in postnatal degeneration of photoreceptors.

Nontraumatic Compartment Syndrome in a Patient with Protein S Deficiency: A Case Report

CASE

Protein S deficiency, a hypercoagulable thrombophilia, often results in venous thromboembolism. Nontraumatic compartment syndrome in a patient with protein S deficiency has not been well publicized. Herein, we present a rare case of nontraumatic compartment syndrome of the hand and the thigh in a 48-year-old woman with a known history of protein S deficiency; emergency fasciotomies were needed.

CONCLUSION

Based on our patient and a review of the current literature, we advocate for a heightened awareness of compartment syndrome in patients with protein S deficiency.

Serum proteins C and S levels as early biomarkers for kidney dysfunction in hemophilic patients

BACKGROUND

Hemophilia is an inherited genetic disease characterized by the inability to coagulate blood after injury. The rationale of the current study was to evaluate serum proteins S and C and correlate to kidney function test in hemophilic patients for early diagnosis of abnormality in renal function.

SUBJECTS AND METHODS

This study was conducted on 80 males subjects divided into four groups. Group I: Control: Healthy subjects. Group II: Renal dysfunction (serum Creatinine >2mg/dl): Group III: Hemophilic patients. Group IV: Hemophilic patients with renal disorder. Serum urea, creatinine, sodium, potassium, protein C and protein S level were determined.

RESUTS

Protein C and S levels showed a significant decrease in hemophilic/and with renal dysfunction (P < 0.001, p<0.001). The level of plasma protein C and S levels were positively correlated with increased urinary albumin (P < 0.01). Urinary albumin was increased about 15 folds in hemophilic patients with renal dysfunction and nephrotic patients as compared with the control group. The cut-off value in 90% patients at the hemophilic patients with renal dysfunction 70%. Positive correlations were observed between urinary albumin (r=0.66), and creatinine (r=0.73).

CONCLUSION

These biomarkers showed good predictive values with regard to ROC-AUC (0.41 and 0.75 for Proteins C and S, respectively).

Screening of potential biomarkers in uterine leiomyomas disease via gene expression profiling analysis

The present study aimed to screen potential biomarkers for uterine leiomyomas disease, particularly target genes associated with the mediator of RNA polymerase II transcription subunit 12 (MED12) mutation. The microarray data of GSE30673, including 10 MED12 wild-type myometrium, 8 MED12 mutation leiomyoma and 2 MED12 wild-type leiomyoma samples, were downloaded from the Gene Expression Omnibus database. Compared with myometrium samples, differently-expressed genes (DEGs) in the MED12 mutation and wild-type leiomyoma samples were identified using the Limma package. The two sets of DEGs obtained were intersected to screen common DEGs. The DEGs in the MED12 mutation and wild-type leiomyoma samples, and common DEGs were defined as group A, B and C. Gene Ontology (GO) and pathway enrichment analyses were performed using the Database for Annotation, Visualization and Integrated Discovery online tool. Based on the Kyoto Encyclopedia of Genes and Genomes database, pathway relation networks were constructed. DEGs in GO terms and pathways were intersected to screen important DEGs. Subsequently, a gene co-expression network was constructed and visualized using Cytoscape software. Reverse transcription-quantitative polymerase chain reaction was used to detect the expression levels of important DEGs. A total of 1,258 DEGs in group A were screened, and enriched for extracellular matrix (ECM) organization and ECM-receptor interaction. In addition, a total of 1,571 DEGs in group B were enriched for cell adhesion. Furthermore, 391 DEGs were involved in extracellular matrix organization. Pathway relation networks of group A, B and C were constructed with nodes of 48, 39, and 28, respectively. Finally, 135 important DEGs were obtained, including Acyl-CoA synthetase medium-chain family member 3, protein S (α) (PROS1) and F11 receptor. A gene co-expression network with 68 nodes was constructed. The expression of caspase 1 (CASP1) and aldehyde dehydrogenase 1 family member A1 (ALDH1A1) was significant higher in SK-UT-1 compared with that in PHM1-31 cells, while the expression of PROS1 was significant lower in SK-UT-1 cells. These results that CASP1, ALDH1A1 and PROS1 may be potential biomarkers for uterine leiomyomas. Furthermore, hematopoietic prostaglandin D synthase and carbonyl reductase 3 (CBR3) may be particular genes associated with the MED12 mutation in this disease.

Detection of procoagulant imbalance

Each individual possesses his/her own endogenous-thrombin-potential (ETP) (i. e. the ability to generate thrombin) which depends on the relative strength of the pro- and anticoagulant drivers operating in plasma. This ability depends in turn on the clinical conditions in which the balance between the two drivers is variably affected. One of the major determinants of this balance is the factor (F)VIII-protein C(PC) axis and its effect can be conveniently explored by the thrombin generation procedures with results expressed as ETP ratio with/without thrombomodulin (TM) (ETP-TM ratio). Furthermore, owing to the many feedback mechanisms mediated by thrombin (e. g. activation of PC, FXI, FV, FVIII, platelets etc.) it is also possible that any perturbation of the balance between pro- and anticoagulants that may occur in plasma even outside the FVIII-PC axis could result in an increased ETPTM ratio and therefore may suggest a procoagulant imbalance. Indeed, other non-coagulation moieties (e. g. microparticles, neutrophil extracellular traps, pro-inflammatory cytokines and others) circulating in blood of patients with various clinical conditions may also contribute to the procoagulant imbalance even when FVIII and/or PC are apparently normal. It can be postulated that dual ETP measurements performed in the presence and absence of TM with results expressed as their ratio may be the candidate procedure to detect subtle procoagulant imbalance in many clinical conditions characterised by an increased risk of thromboembolism. This article aimed at reviewing the clinical conditions in which evidence for the value of the ETP-TM ratio has been provided.

Activated protein C light chain provides an extended binding surface for its anticoagulant cofactor, protein S

Protein S anticoagulant cofactor sensitivity and PAR1 cleavage activity were assayed for 9 recombinant APC mutants.Residues L38, K43, I73, F95, and W115 on one face of the APC light chain define an extended surface containing the protein S binding site.

Increased Circulating and Urinary Levels of Soluble TAM Receptors in Diabetic Nephropathy

TAM receptors (Tyro3, Axl, and Mer) have been implicated in innate immunity. Circulating TAM receptor soluble forms (sTyro3, sAxl, sMer) are related to autoimmune disorders. We investigated TAM and their ligand protein S in patients with diabetes. Urinary and plasma levels of protein S, sTyro3, sAxl, and sMer were determined in 126 patients with diabetes assigned to a normoalbuminuric or macroalbuminuric (urinary albumin excretion <30 mg/24 hours and >300 mg/24 hours, respectively) study group and 18 healthy volunteers. TAM and protein S immunostaining was performed on kidney biopsy specimens from patients with diabetic nephropathy (n = 9) and controls (n = 6). TAM expression and shedding by tubular epithelial cells were investigated by PCR and enzyme-linked immunosorbent assay in an in vitro diabetes model. Patients with macroalbuminuria diabetes had higher circulating levels of sMer and more urinary sTyro3 and sMer than normoalbuminuric diabetics. Increased clearance of sTyro3 and sMer was associated with loss of tubular Tyro3 and Mer expression in diabetic nephropathy tissue and glomerular depositions of protein S. During in vitro diabetes, human kidney cells had down-regulation of Tyro3 and Mer mRNA and increased shedding of sTyro3 and sMer. Renal injury in diabetes is associated with elevated systemic and urine levels of sMer and sTyro3. This is the first study reporting excretion of sTAM receptors in urine, identifying the kidney as a source of sTAM.

Hemostatic Changes Associated With Increased Mortality Rates in Hospitalized Patients With HIV-Associated Tuberculosis: A Prospective Cohort Study

Background

Mortality rates remain high for human immunodeficiency virus (HIV)-associated tuberculosis, and our knowledge of contributing mechanisms is limited. We aimed to determine whether hemostatic changes in HIV-tuberculosis were associated with mortality or decreased survival time and the contribution of mycobacteremia to these effects.

Methods

We conducted a prospective study in Khayelitsha, South Africa, in hospitalized HIV-infected patients with CD4 cell counts <350/µL and microbiologically proved tuberculosis. HIV-infected outpatients without tuberculosis served as controls. Plasma biomarkers reflecting activation of procoagulation and anticoagulation, fibrinolysis, endothelial cell activation, matricellular protein release, and tissue damage were measured at admission. Cox proportional hazard models were used to assess variables associated with 12-week mortality rates.

Results

Of 59 patients with HIV-tuberculosis, 16 (27%) died after a median of 12 days (interquartile range, 0-24 days); 29 (64%) of the 45 not receiving anticoagulants fulfilled criteria for disseminated intravascular coagulation. Decreased survival time was associated with higher concentrations of markers of fibrinolysis, endothelial activation, matricellular protein release, and tissue damage and with decreased concentrations for markers of anticoagulation. In patients who died, coagulation factors involved in the common pathway were depleted (factor II, V, X), which corresponded to increased plasma clotting times. Mycobacteremia modestly influenced hemostatic changes without affecting mortality.

Conclusions

Patients with severe HIV-tuberculosis display a hypercoagulable state and activation of the endothelium, which is associated with mortality.

New functional assays to selectively quantify the activated protein C- and tissue factor pathway inhibitor-cofactor activities of protein S in plasma

Essentials Protein S is a cofactor of activated protein C (APC) and tissue factor pathway inhibitor (TFPI). There are no assays to quantify separate APC and TFPI cofactor activities of protein S in plasma. We developed assays to measure the APC- and TFPI-cofactor activities of protein S in plasma. The assays were sensitive to protein S deficiency, and not affected by the Factor V Leiden mutation.

SUMMARY

Background Protein S plays an important role in the down-regulation of coagulation as cofactor for activated protein C (APC) and tissue factor pathway inhibitor (TFPI). Aim To develop functional assays to quantify the APC- and TFPI-cofactor activities of protein S in plasma. Methods APC- and TFPI-cofactor activities of protein S in plasma were measured using calibrated automated thrombography in protein S-depleted plasma supplemented with a small amount of sample plasma either in the presence of anti-TFPI antibodies and APC (APC-cofactor activity) or at excess full-length TFPI without APC (TFPI-cofactor activity). Total and free protein S levels in plasma were measured by ELISAs. Results Average APC-cofactor activities of protein S were 113%, 108% and 89% in plasma from normal individuals (n = 15), FV Leiden heterozygotes (n = 14) and FV Leiden homozygotes (n = 7), respectively, whereas the average APC-cofactor activity of protein S in plasma from heterozygous protein S-deficient individuals (n = 21) was significantly lower (55%). Similar trends were observed for the TFPI-cofactor activity of protein S, with averages of 109%, 115% and 124% in plasma from individuals with normal protein S levels and different FV Leiden genotypes, and 64% in plasma from protein S-deficient patients. APC-cofactor activities of protein S correlated significantly with free and total protein S antigen levels, whereas TFPI-cofactor activities correlated less with protein S antigen levels. Conclusion We have developed functional protein S assays that measure both the APC- and TFPI-cofactor activities of protein S in plasma, which are hardly if at all affected by the FV Leiden mutation.

Protein S Heerlen mutation heterozygosity is associated with venous thrombosis risk

Hereditary Protein S (PS) deficiency is a rare coagulation disorder associated with an increased risk of venous thrombosis (VT). The PS Heerlen (PSH) mutation is a rare S501P mutation that was initially considered to be a neutral polymorphism. However, it has been later shown that PSH has a reduced half-life in vivo which may explain the association of PSH heterozygosity with mildly reduced levels of plasma free PS (FPS). Whether the risk of VT is increased in PSH carriers remains unknown. We analyzed the association of PSH (rs121918472 A/G) with VT in 4,173 VT patients and 5,970 healthy individuals from four independent case-control studies. Quantitative determination of FPS levels was performed in a subsample of 1257 VT patients. In the investigated populations, the AG genotype was associated with an increased VT risk of 6.57 [4.06–10.64] (p = 1.73 10⁻¹⁴). In VT patients in whom PS deficiency was excluded, plasma FPS levels were significantly lower in individuals with PSH when compared to those without [72 + 13 vs 91 + 21 UI/dL; p = 1.86 10⁻⁶, mean + SD for PSH carriers (n = 21) or controls (n = 1236) respectively]. We provide strong evidence that the rare PSH variant is associated with VT in unselected individuals.

Plasma hypercoagulability in the presence of thrombomodulin but not of activated protein C in patients with cirrhosis

BACKGROUND AND AIMS

Cirrhosis significantly changes all hemostasis steps. Recent studies suggest that cirrhosis is associated with a coagulopathy leading to a hypercoagulable state. The underlying mechanisms are not fully understood, but protein C deficiency is probably a major determinant of this phenotype. The aim of this study was to compare the results of thrombin generation assays performed with addition of thrombomodulin or activated protein C to assess the effect of by-passing the protein C activation step in cirrhotic patients and healthy controls.

METHODS

Fifty-eight patients with cirrhosis and 26 healthy controls were prospectively included in this study. Thrombin generation was determined in platelet-poor plasma using 5 pM of tissue factor and 4 nM of phospholipids, without and with external addition of 1 nM thrombomodulin or 4 nM activated protein C. All results were normalized with the values of a pool of normal plasma samples to limit inter-plate variability.

RESULTS

When thrombin generation assays were performed in the presence of thrombomodulin, endogenous thrombin potential (ETP) and ETP with/ETP without TM ratio were significantly higher in cirrhotic patients than in healthy controls (P < 0.0001). Moreover, these values progressively increased with cirrhosis severity. When thrombin generation assays were performed with activated protein C, all thrombin generation parameters were comparable between healthy controls and cirrhotic patients, despite an acquired protein S deficiency.

CONCLUSION

In the presence of activated protein C, no hypercoagulability was observed, adding to the current evidence that acquired protein C deficiency plays a key role in the coagulation imbalance.

An Overview of Thrombophilia and Associated Laboratory Testing

Venous thromboembolism, usually entailing deep vein thrombosis, pulmonary embolism, or both, is a complex and multifactorial disorder, in which a number of putative conditions interplay and finally contribute to propel the individual risk over a certain degree, so ultimately culminating in the development of venous occlusive disorders. Thrombophilia is commonly defined as a propensity to develop venous thromboembolism on the basis of an underlying hypercoagulable state attributable to inherited or acquired disorders of blood coagulation or fibrinolysis. The thrombophilic conditions are conventionally classified as inherited (or genetically determined) and acquired. The former include deficiencies of natural anticoagulants such as antithrombin, protein C, protein S, increased values of clotting factors (especially factor VIII), as well as prothrombotic polymorphisms in genes encoding for factor V (i.e., factor V Leiden) and prothrombin. The latter conditions mainly entail antiphospholipid antibody syndrome, malignancy, acquired elevations of coagulation factors or acquired reduction of natural inhibitors, or hyperhomocysteinemia. Deepened knowledge of all potential risk factors, as well as the clear understanding of their role in the pathophysiology of venous thrombosis, are both essential to help achieve a faster and more efficient diagnosis of this condition as well as a more effective prophylaxis of patients at higher risk and treatment of those with manifest disease.

Decreased Activity of the Protein C Anticoagulant Pathway in the Early Hours of Paroxysmal Atrial Fibrillation

BACKGROUND

Increased coagulation activity has been established in paroxysmal atrial fibrillation (PAF), but data on the anticoagulant system are scarce.

PURPOSE

To examine the protein C anticoagulant pathway in the early hours of the disease.

MATERIALS AND METHODS

Fifty-one patients (26 men and 25 women; mean age 59.84 ± 1.60 years) and 52 controls (26 men and 26 women; mean age 59.50 ± 1.46 years) were selected for the study. Protein C antigen and its activity, total protein S, free protein S and its activity, soluble forms of endothelial protein C receptor (sEPCR), and thrombomodulin (sTM) were examined in the plasma.

RESULTS

The indicators were studied in patients between the 2nd and the 24th hour after the onset of arrhythmia. Levels of protein C were significantly elevated in patients compared to controls (111.40% ± 6.66% vs 94.83% ± 4.47%; P = .039). Protein C activity showed significant reduction in PAF (73.13% ± 5.80% vs 103.3% ± 3.80%; P < .001). Total protein S levels did not differ significantly (108.20% ± 4.07% vs 102.40% ± 3.65%; P = .30). Free protein S (76.81% ± 6.01% vs 122.10% ± 3.97%; P < .001) and its activity (71.39% ± 6.27% vs 119.50% ± 6.54%; P < .001) were reduced in patients. Higher levels of sEPCR (203.10 ± 10.33 vs 133.10 ± 7.37 ng/mL; P < .001) and sTM (6.50±0.40 vs 4.48±0.28 ng/mL; P < .001) were measured in PAF.

CONCLUSION

Protein C activity is reduced still in the first hours (until the 24th hour) of PAF clinical manifestation, determining reduced activity of the anticoagulant pathway as a whole. The established low levels of free protein S and its activity as well as low sEPCR and sTM levels are a possible explanation of the changes in protein C activity.

Impact of HIV infection on the haemostatic response during sepsis and malaria

Patients positive for the human immunodeficiency virus (HIV) are more susceptible to sepsis and malaria, two conditions known to activate the coagulation system. As chronic HIV infection also influences haemostatic mechanisms, we determined the influence of HIV co-infection on coagulation, anticoagulation and the endothelium during sepsis or malaria. We performed a prospective observational study in 325 subjects with or without HIV infection (103 with sepsis, 127 with malaria and 95 asymptomatic controls) in an HIV endemic area in Central Africa. We measured plasma biomarkers indicative of activation of distinct haemostatic mechanisms. Sepsis and malaria had similar effects with elevated markers of coagulation, reduced anticoagulation markers and activation of endothelium. In particular, asymptomatic HIV infection reduced the plasma levels of the anticoagulant co-factor free protein S, and increased activation of the vascular endothelium, which were not normalized by combination antiretroviral therapy. HIV co-infection during sepsis and malaria caused more profound changes in free protein S and von Willebrand factor in sepsis and malaria, and ADAMTS13 in sepsis, while not influencing sepsis- or malaria-induced coagulation activation. These results show for the first time that HIV infection augments selective haemostatic changes during sepsis and malaria, which may contribute to the enhanced morbidity of these conditions in HIV patients.

The unexpected finding of a splenic infarction in a patient with infectious mononucleosis due to Epstein-Barr virus

The authors present a case of a 24-year-old man with infectious mononucleosis (IM) due to Epstein-Barr virus (EBV). Among his symptoms, he reported abdominal pain in the upper left quadrant. An abdominal ultrasound and CT revealed an extensive splenic infarction. During the acute stage of this disease, the thrombophilic screening revealed reduced free protein S and elevated factor VIII, with normalisation on re-evaluation 6 weeks later. Splenic infarction is a very rare complication of IM due to EBV but should be considered in patients presenting abdominal pain. A hypercoagulability state should be investigated. To our knowledge, this is the first described case of a splenic infarction in a patient with IM due to EBV associated with a transient reduction of protein S and elevation of factor VIII. Thus, this work promotes the importance of including these factors in the thrombophilic screening conducted during the investigation of similar cases.